# Astro Test/Second Semester 2017

Main-sequence stars are in hydrostatic equilibrium, which means a balance between a star's
(a) hydrogen-burning and helium-burning processes.
(b) hydraulic and static forces.
(c) nuclear fusion and nuclear fission processes.
(d) inward gravitational forces and outward forces due to core pressure
Click the card to flip 👆
1 / 50
Terms in this set (50)
High temperatures and pressures are required to produce nuclear reactions because this helps
(a) convince atomic nuclei to get to know each other.
(b) atomic nuclei attract each other.
(c) to overcome the electrical repulsion between atomic nuclei. (d) to overcome the gravitational attraction between atomic nuclei.
As a main-sequence star evolves, steadily converting hydrogen to helium in its core, the outer layers of the star gradually
(a) become cooler and contract. (b) become cooler and expand.
(c) become hotter and expand.
(d) become hotter and contract. (e) [There is no change in the temperature and size of the outer layers.]